When a sudden and widespread crisis, such as a natural disaster or a terrorists attack occurs, communication channels may become saturated beyond their maximum capacity. Further, the percentage of emergency calls made using wireless devices is increasing at a rapid rate. For example, it is estimated that approximately thirty percent of emergency calls that were made in 2000 were done so by wireless communication device users. This is a ten-fold increase from just ten years earlier. It is anticipated that this increasing rate of wireless emergency calls will continue in the future.
Wireless callers may use a wide range of wireless communication systems to initiate an emergency call. In general, wireless communication systems include communication mechanisms necessary to ensure the completion of an emergency call reliably.
Ad hoc networks are self-forming networks which can operate in the absence of any fixed infrastructure, and in some cases the ad hoc network is formed entirely of mobile nodes. An ad hoc network typically includes a number of geographically-distributed, potentially mobile units, sometimes referred to as “nodes,” which are wirelessly connected to each other by one or more links (e.g., radio frequency communication channels). The nodes can communicate with each other over a wireless media with or without the support of an infrastructure-based wired network.
A wireless mesh network is a collection of wireless nodes or devices organized in a decentralized manner to provide range extension by allowing nodes to be reached across multiple hops. In a multi-hop network, communication packets sent by a source node can be relayed through one or more intermediary nodes before reaching a destination node. A large network can be realized using intelligent access points (IAP) which provide wireless nodes with access to a wired backhaul. A mesh network therefore typically comprises one or more IAPs (Intelligent Access Points), and a number of APs (Access Points), which provide data service to STAs (subscriber stations). An AP can connect to IAP directly or through multi-hop route. Requirements for supporting an emergency call impose additional challenges for Ad-hoc networks. For example, there are additional operation challenges associated with routing a high number of emergency calls from mobile stations to a geographically appropriate public safety authority (i.e. Public Safety Answering Point (PSAP)).
Generally, Ad-hoc networks and mesh networks have limited bandwidth between any two nodes. Therefore, in emergency situations when a large number of emergency calls originate from a particular location, there are bottlenecks between nodes in the mesh network. Furthermore, in emergency situations which affect large areas (e.g. natural disasters, terrorist attacks in public areas) some infrastructure nodes of the mesh network may be destroyed, reducing the bandwidth even more. In this case, even when the number of voice call initiators is relatively small, the network may not support such calls that require low delay and jitter.
Although current systems can preempt low priority calls, the congestion problem in the mesh network will not be resolved because the priority of all the emergency calls may be the same. Since conventional call admission and congestion control schemes may not resolve this problem, delays and even disruption of services may occur due to timeouts in route and call establishment processes. This will prevent the PSAPs from being able to communicate with mobile users and thereby preventing the emergency services personnel from providing the necessary assistance. Even when a limited number of users can reach PSAPs, PSAPs may not have the correct estimation of the people affected by the incident in a critical time interval. When there is enough bandwidth, depending on the incident severity, there may not be enough emergency personnel to respond individual calls.
Accordingly, there is a need for a method and apparatus to aggregate information to ensure reliable completion of emergency calls in a wireless communication system.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.